Spark-plug.



J. W. MEAKER.

SPARK PLUG.

APPLICATION HLED 111111.25, 1912.

Patented Sept. 16, 1913.

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niacin.

JOHN W. 'MEKEBQ 0F DETLROIT, MICHIGAN,

Specification of-Letters Patent.

Szenen-PLUG.

Patented Sept. 16.51913.

'Application led March 25, 1912. Serial lia-685,934.

To'aZZ whom it may concern.'

Be it linownthat I, JOHN WV. MEAKER, a citizen ofthe United States of America, residin at Detroit, in the'county of llayne and State of Michigan, have invented certain new and useful Improvements in SparkePlugs, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to improvements in spark phigs v.and its object is lto provides. simple, cheap and ,efiicie'nt construction 1n which the insulating member Vis .quickly insertible in the bushing andfmay be adjusted therethrough to any desired position, 4and also embodying a construction of transparent head with a spark gap therein, having certain new and yuseful features all as hercina'fter more fully set forth.

The invention consists ,in the matters V'helreinafter set forth .and more particularly pointed out in the claims reference being had to the accompanying drawings 'in which- Figure 1 is a vertical section through la spark plug embodying the invention; Fig.

' 2 is a' section of the same on the -line 11-11 of Fig. 1; Fig. 3 is a detail showing an iuverted lplan view of the transparent head; Fig. 4 is an elevation of the lower end of the spark plug; Fig. 5 isa longitudinal ver- -tical sectionthrough a spark -plug embodyv ing a modified construction; and Fig. G is Aa simil-ar view showing a further 'modified construction. i, A

As shown -1n Fig. 1, a bushing 1 1s formed in the usual manner with an externally 'screwthreaded portion to engage a screwthreaded opening in the cylinder of an engine and also formed with a-hexagonal head ,portion for .the engagement-of a wrench-by means of which the bus'hingisescrewed into place. The hexagonal headis preferably provided with a number of grooves 2 to give a greater radiating surface to the head so that it will .cool rapidly. The bushing is formed with an axial bore extending there through and it is preferably linternally screwthreaded throughout its length to receive .an externally screwthreaded tubular member or binding sleeve 3 which is formed with flattened sides .at its inner end forminga wrench lhold ll by means o'f which the sleeve may be screwed into the bore of the bushing.' The inner or upper end of the sleeve 3 forms a shoulder to support the insulating plug 5 which is preferably formed of porcelain inthe usual manner with an annular rib 6 .intermediate its endswhich fits 'within the boreof the bushing and forms shoulders adapted to `be engaged by suitable packing rings-77 one of said rings being interposed between 'the shoulder and hold lthe insulating plug in place. Obviously "the insulating p'lug may be adjusted within the bore by adjust-ing the sleeveand docking rings which form movable shoulders within the 'bushingto clamp the rib on the plug between them. f

rod secured in the usual manner in an axial 'bore in the insulating plug forms an electrode 10. The vlower projecting end of the rod l is reduced in diameter and the u lower end of the sleeve 3 is 'preferably partially closed by a plate'l'l 'having an axial opening through which the end of the electrode projects. The plate is also provided with a plurality .of openings 12 surrounding the center opening and cutting into said opening so that a' plurality of sparking points is formed' on the plate around the electrode of the plug. jecting flange 13 at the extreme 'lower end of the sleeve 3 forms a seat for the plate 11 and this plate is preferably made of a nickel alloy or other suitable metal not readily destroved by heat.

The 'head of the bushing '1 is formed with 'an upwardly extending 'tubular portion 14 which is enlarged at its upper end and internally screwthreaded to form a socket to receive ahead 15 which is preferably formed of glass or other transparent material. This transparent head is externally screwthread ed at its lower end 4to engage the socket "14 and is seated within the socket upon a shoulder l1G formed by the'enlarged upper end of the tubular extension of the bushing, which tubular portion is lformed with a series of air holes 17 below the socket 14 to admit air tothe interior of the head and cool the An inwardly pro-' saine so that the glass will not become overheated and crack.

The upper projecting end'of the electrode l0 within the insulating plug, is also reduced in diameter and is spaced from a second electrode 18 which is carried by a cap 1f) fitting upon the upper end of the head 15. A series of grooves 20 in the upper end otl the head permit a circulation of air through the head beneath the cap. A suitable plate or spider 21 is secured to `the rod forming the electrode 18 near the inner end thereof to engage suitable seats or notches formed in the inner side of the head 15 and the outer end of the rod projects through an opening in the cap 19 and is screwthreaded to receive a. binding nut 22 b v means of which the cap is secured in place and the electrode adjustably held. The rod forming the electrode preferably engages a screwsthreaded opening in the spider 21 so that said rod may be adjusted through the spider to move its sparking point toward or from the sparking point of the electrode 10.

In this construction the spark gap is located within a head formed entirely of glass or other transparent material so that the spark may be readily observed and the construction is such that the head is ventilated and thoroughly cooled to prevent the cracking of t-he glass.

In Fig. 5, a construction is shown in which the socket for receiving the transparent head is formed integral with the upper end of an externally screwthreaded sleeve 23 adapted to be screwed into the upper end of the bore of the bushing. As in the construction shown in Fig. 1, this socket 24 is internally screwthreaded to receive the screwth'readed lower end of the transparent head 25 which seats within the socket and a series of holes 2G for Ventilating the head are formed in 'the tubular extension of the sleeve. The lower end of this sleeve 23 forms a shoulder to engage the upper washer 7 which is imposed between the end ofV the sleeve and the annular rib G on the insulating plug.

In the construction shown in Fig. G, the spark gap and transparent head are dispensed with and the bushing 27 is formed as in the other constructions with an axially screwthreaded bore, but the screw thread is stopped at a short distance from the klower end of the bore to form a stop 32 for the vlower sleeve 33 which is formed through screw threads at its upper end only, the remainder of the sleeve being formed plain so that it will pass through the plain loweiend 'of the bore. Said sleeve 3? is thus held by its screw 'threads against any possibility of werking loose and dropping out, and it may be readily screwed into the bore from the upper end thereof. The upper or inncr end of the sleeve 33 forms a shoulder to oppose the lower 'shoulder 011 the insulating plug 29 formed by the annular rib thereon, and the inner end of' the screwthreaded sleeve 28 which is screwed into the upper' end of the bore, forms a shoulder to oppose the upper shoulder on the plug.v rlhe said insulating plug is thus held by clamping its rib between said sleeves with the packing rings7 interposed between their inner ends and the said shoulders formed by the rib. When so held, the upper end of the plug extends outwardly through the outer 'open end of the ring 28 and the electrode 30 extends-,outward through the outer en d of said plug where it is provided with a binding nut 31 for attaching an electrical conductor thereto.

This construction of spark plug is very cheap to manufacture owing to the construction of the bushing with its axial screwthreaded bore and the sleeves therein which form adjustable seats for the insulating plug. Obviously, changes in the construction and arrangement of parts may be made without departing from the spirit of my invention and I do not wish to limit myself to the particular form and arrangement shown. Having thus fully described my invention what I claim is z- 1. In a spark plug, the combination of a bushing having an axial screwthreaded bore of uniform diameter extending through the bushing, an insulating plug in the bushing formed with an annular rib,l `externally screwthreaded tubular members within the bushing surrounding the upper and'lower ends of the insulating plug and forming shoulders at their inner ends -to oppose the shoulders formed by the rib on the plug, an electrode carried by the insulating plug and extending longitudinally therethrough, a. tubular extension on the bushing provided with air openings and formed with a seat, a transparent head having open ends and seated within said seat, an electrode extending through the upper open end of the head, and means for adjustably securing the electrodein place upon the headwith its inner end spaced from the electrode carried by the insulating plug to form a spark gap within the head, the sleeves and plugs being together longitudinallyA adjustable in the bushing, and an electrode on the lower sleeve end to engage the screwthreaded bore and an electrode on the lower sleeve in operative 10 formed with a plain lower end, the screw relation to the plug electrode.

thread of the bore being stopped at a ds- In testimony wliereof I aiiix my signature tance from the lower end of the bore to form in presence of two witnesses.

' a stop for the sleeve,` and an externally sorewthreaded member screwed'into the bore v JOHN W' MEAKER above the enlargement on the insulating Witnesses: plug, the sleeves and plugs being together ANNA M. DORR,

' longitudinally adjustable in the bushing, and C. R. STIGKNEY. 

